Add HTTP

It's really slow for some reason. Not sure why.
I think this is causing the slowness... Maybe you are waiting until the connection is closed by the server. I tried using  the `read` function and it worked in less than a second. The only thing I don't know is the size of the buffer that we need. There is a `Content-Length` header in the http response, but I think it would be overkill for a code example like this one (you would need to read the headers, get the Content-Length using a regex, then read the rest).

So I suggest this, which should be ok for most websites:

```
let mut buffer = [0, ..100000];
socket.read(buffer).ok();
Vec::from_slice(buffer)
```

My only concern is that all unused bytes of the buffer will be translated as whitespace. Do you have an idea to avoid it?